In general, as time goes on after foods have been stored in a box, nutrients of the foods are gradually destroyed, and the freshness of the foods may be degraded.
In order to solve the above problem, foods may be put into a food box and ultraviolet rays may be irradiated onto the foods, or the foods may be individually packaged, or may be kept refrigerated.
However, when the ultraviolet rays may be irradiated onto the foods or the foods are individually packaged, the freshness and the nutrients of the foods may be maintained only for a very short time, and the foods may be spoiled if a predetermined time elapses. However, when the foods are kept refrigerated, although the foods may be stored for a long time, most of nutrients may be destroyed.
As related arts, there are Korean Unexamined Patent Publication No. 10-2007-0098422 and Korean Patent Registration No.